docs: def com_google_fonts_check_metadata_copyright(family_metadata):
    """METADATA.pb: Copyright notice is the same in all fonts?"""
    copyright = None
    fail = False
    for f in family_metadata.fonts:
      if copyright and f.copyright != copyright:
        fail = True
      copyright = f.copyright
    if fail:
      yield FAIL, ("METADATA.pb: Copyright field value"
                   " is inconsistent across family")
    else:
      yield PASS, "Copyright is consistent across family"